As twin brothers sat in separate jails Tuesday afternoon, an autopsy determined a man whose body was found in a plastic container, encased in concrete and buried in a Winder backyard, died of blunt force trauma to the back of the head.

Before the autopsy could begin, investigators had to use a sledgehammer to remove the hardened concrete from the human remains. But long before the autopsy was completed, investigators said the remains were believed to be those of a journalist reported missing from Pensacola, Fla., nearly a month ago.

Friends of Sean Christopher Dugas, 30, reported him missing on Sept. 13, Chief Chip Simmons with Pensacola police told The Atlanta Journal-Constitution on Tuesday. Dugas had not been heard from since Aug. 27, Simmons said.

It will likely be Wednesday before investigators positively identify the Winder remains, based on dental records, fingerprints and a tattoo.

The 31-year-old twins, Christopher and William Cormier, were arrested Monday night after a massive concrete block was pulled from a Barrow County backyard, Winder police Chief Dennis Dorsey told the AJC.

The brothers had not yet been formally charged as of Tuesday night but were expected to face numerous charges pending the outcome of the investigation, Dorsey said. (An earlier report that they had been charged with concealing a death was incorrect.)

“We don’t even have a cause of death yet,” Dorsey said by phone Monday night. “If the autopsy shows what we expect it will show, the charges could be upgraded.”

Just how and why a body was buried in a backyard remained unknown late Tuesday. Outside of his home, the twins’ father said he was shocked by the developments and said he didn’t know what led to the gruesome discovery.

Dugas, who previously worked as a reporter for the Pensacola News-Journal, was supposed to meet a female friend for lunch Aug. 27. But when the friend arrived at his home to pick him up, he wasn’t there, said Pensacola police Capt. David Alexander.

The friend left a note for Dugas and tried to reach him for several days, Alexander said. When the woman returned to the home Sept. 7, it was empty except for a television, according to police.

Investigators in Florida had been actively working Dugas’ disappearance as a missing persons case before information led them to contact police in Winder, Simmons said. Neighbors of Dugas told police they saw men loading items into a U-Haul truck at the home on Sept. 3

Dorsey said his department received a call Monday morning from the Pensacola Police Department regarding Dugas, who allegedly was last seen with the Cormier twins.

The brothers, who previously lived in Pensacola, told neighbors they were moving to Georgia, and the missing man was coming along, Dorsey said.

“They showed up at the father’s address about three weeks ago,” Dorsey said.

But the brothers’ friend was not with them, Dorsey said. The two told their father, who rents the Winder home, that their friend had moved somewhere else, the chief said.

The Cormiers also told their father that their friend’s dog had died, and they planned to bury it in the backyard of the family home, in the 200 block of Sixth Avenue in Winder, Dorsey said.

“They claimed they buried the dog,” Dorsey said.

Investigators arrived at the home Monday, executed a search warrant and, in the backyard, spotted an area where something had been buried, Dorsey said.

It wasn’t a dog. With heavy machinery owned by the city, investigators unearthed a large plastic container that had been encased in concrete, Dorsey said. By cutting around the bottom of the container, investigators found the human remains, he said.

“We transported the large block of concrete with the body enclosed to the crime lab,” Dorsey said.

The GBI and Pensacola police were alerted to the findings, and both agencies are assisting Winder police with the investigation, Dorsey said. Simmons said two Pensacola investigators arrived in Winder on Tuesday.

After using a sledgehammer to free the body from concrete, an autopsy was being conducted by the GBI to determine the person’s identity and a cause of death, an agency spokesman said. But investigators in both states said they have a strong suspicion on the identification of the remains.

“We do believe there is a connection,” Simmons said.

Police said they do not believe the Cormiers’ father, who is cooperating with the investigation, will face charges.

At the Pensacola newspaper, where Dugas worked until 2010, former colleagues and friends struggled with the news happening nearly 400 miles away in Winder.

“Several of us had tried to reach out and find him,” Kim Thomas, the newspaper’s deputy managing editor for digital, said by phone Tuesday night. “We thought he had up and moved and not told anyone.”

Dugas grew up in Pensacola, was an Eagle Scout and attended the University of West Florida, Thomas said. With a long, scraggly beard, Dugas had a free-spirited personality and wide range of interests, she said.

“He didn’t look like a reporter, but he had the soul of a reporter,” Thomas said. “That was just him. He always did what was unexpected.”